The present invention relates to metal-oxide-semiconductor field-effect transistors (MOSFET), and more specifically, to end-bonded metal contacts on carbon nanotubes.
The MOSFET is a transistor used for amplifying or switching electronic signals. The MOSFET has a source, a drain, and a metal oxide gate electrode. The metal gate is electrically insulated from the main semiconductor n-channel or p-channel by a thin layer of insulating material, for example, silicon dioxide or glass, which makes the input resistance of the MOSFET relatively high. The gate voltage controls whether the path from drain to source is an open circuit (“off”) or a resistive path (“on”).
N-type field effect transistors (NFET) and p-type field effect transistors (PFET) are two types of complementary MOSFETs. The NFET uses electrons as the current carriers and is built with n-doped source and drain junctions. The PFET uses holes as the current carriers and is built with p-doped source and drain junctions.
The evolution of modern complementary metal-oxide semiconductor (CMOS) technology continuously scales down not only the device channel length but also the contact length. As the channel length reaches tens of nanometers, the contact resistance becomes comparable with the channel resistance, and hence gradually limits the transistor drive current.